Abstract: Studies on allocation of nitrogen (N), phosphorus (P) and soluble sugar in plants of tropical cloud forest play an important role in understanding the growth and adaptation of plants to the environment. We measured the contents of N, P and soluble sugar in the twigs and leaves from the 282 species of tropical cloud forests in three sites (i.e., Bawangling Mountain (BWL), Jianfengling Mountain (JFL) and Limushan Mountain (LMS)) of Hainan Island, aiming to clarify the correlations of N, P, and soluble sugar in different vegetative organs. The results showed that the contents of N, P and soluble sugar in leaves were significantly higher than those in twigs. In twigs and leaves, the contents of soluble sugar were (15.06±9.4) and (32.14±19.57) g·kg^-1, the contents of N were (3.48±1.02) and (9.51±5.26) g·kg^-1, and the contents of P were(0.23±0.15) and (0.56±0.44) g·kg^-1, respectively. The contents of N and P in the leaves and stems were the highest in LMS and the lowest in BWL. The content of soluble sugar in the twigs of BWL was significantly higher than that in LMS and JFL, whereas the content of soluble sugar in leaves was significantly lower than that of LMS and JFL. In twigs and leaves, there were significantly positive correlations between N and P contents, while soluble sugar contents were not significantly related to P contents. Moreover, N and P contents in twigs were significantly positive correlated with that in leaves, while there was no significant correlation in soluble sugar content between twigs and leaves. In addition, we found that P was a main limiting factor for plant growth and population development in the tropical cloud forests of Hainan Island.

Key words: half-sib family, resistance to disease and insect, variance., fruiting, Pinus koraiensis, growth